Z axis goes up but after 2 sec, motor turn upside down

[mdingena]

Does it behave like in this video?

Z-Axis Motor Not Moving and Unreliable

Here is a video of Z-Axis misbehaving. I can reproduce this issue reliably every time by doing these steps: Power off, position all axes as seen in start of video. Power on, bot is at 0,0,0 Move absolute to -800, 800, 400 Bot moves as seen in video Go back to 0,0,0 (NOT homing, because that makes each axis go individually) The Z-Axis starts to spaz out when X and Y finish their travel. It looks like Z is missing a lot of steps, causing the Axis to slowly drop down again. When Z starts to dece…